The solenoid valve does not reverse.
Encounter the problem of cooling without heating? It may be that the solenoid valve spool or slider is "stuck". This will cause the protection function against blowing cold air to start, the outdoor unit will run, but the indoor unit will not blow hot air, and then stop after the fault light is displayed.
Electromagnetic coil short circuit
When the air conditioner tries to switch to the heating mode, if the solenoid valve coil is short-circuited, the current will surge, and in severe cases, it will burn the fuse on the main control board or cause a trip, resulting in the failure of the whole machine to work normally.
Deformation of solenoid valve slider
Even if the solenoid valve coil is energized, the deformation of the slider may cause the pilot valve spool to fail to act. This will lead to high pressure gas circulation in the compressor too fast, resulting in high temperature and high pressure, which may eventually burn out the insulation layer of the compressor. For the whole system, high pressure may leak to the low pressure end, resulting in poor cooling and heating effect.